"daughter of WILLIAM de Warenne Earl of Surrey & his second wife Maud Marshal of Pembroke (-before 23 Nov 1282, bur Marham, Norfolk). She is named "Ysabella comitissa Harundolliæ quondam Hugonis comitis Harundelliæ uxor" when Matthew of Paris records her foundation of the nunnery of Marham near Lymm"